EMC enhancement for differential devices

Abstract

An apparatus configured to communicate through a differential bus to a device. The apparatus may be configured to disconnect and reconnect the device in response to an abnormal reset event to provide enhanced electromagnetic compliance (EMC).

What is claimed is:  
     
       1. An apparatus comprising: 
       a circuit configured to (i) communicate through a differential bus to a device comprising a hub and (ii) execute firmware configured to disconnect and reconnect said circuit to said device in response to an abnormal reset event to provide enhanced electromagnetic compliance (EMC), wherein said apparatus is configured to communicate with said device through a downstream port.  
     
     
       2. The apparatus according to  claim 1 , wherein said abnormal reset event comprises a single ended zero signal. 
     
     
       3. The apparatus according to  claim 1 , wherein said device is configured to generate said abnormal reset event. 
     
     
       4. The apparatus according to  claim 1 , wherein said device is configured to generate said abnormal reset event in response to a predetermined criteria. 
     
     
       5. The apparatus according to  claim 1 , wherein one line of said differential bus is coupled to a reference voltage through a pull up resistor. 
     
     
       6. The apparatus according to  claim 1 , wherein both lines of said differential bus are coupled to a ground voltage through a first and second pulldown resistor. 
     
     
       7. The apparatus according to  claim 1 , wherein said apparatus is configured to operate when subjected to extreme electrical disturbances without implementing external hardware. 
     
     
       8. The apparatus according to  claim 1 , wherein said apparatus is configured to improve performance of said device to electrostatic discharge (ESD) or electromagnetic fast transmit burst (EFTB) events. 
     
     
       9. The apparatus according to  claim 1 , wherein said device comprises a Universal Serial Bus (USB) peripheral device. 
     
     
       10. The apparatus according to  claim 1 , wherein said apparatus comprises a Universal Serial Bus (USB) hub. 
     
     
       11. The apparatus according to  claim 1 , wherein said device comprises firmware configured to execute code to control said disconnect and reconnect. 
     
     
       12. An apparatus comprising: 
       means for communicating through a differential bus to a device;  
       means for disconnecting from said device; and  
       means for reconnecting said device in response to an abnormal reset event to provide enhanced electromagnetic compliance (EMC), wherein said apparatus (i) comprises a hub and (ii) is configured to communicate with said device through a downstream port.  
     
     
       13. A method for providing enhanced EMC performance in a device, comprising the steps of: 
       (A) generating a zero signal indicating an abnormal reset event in response to a predetermined criteria;  
       (B) communicating through a differential bus to said device; and  
       (C) disconnecting and reconnecting said device in response to said abnormal reset event, wherein said device (i) comprises a hub and (ii) is configured to communicate through a downstream port.  
     
     
       14. The method according to  claim 13 , wherein step (A) further comprises: 
       connecting at least one line of said differential bus to a reference voltage through a pull up resistor.  
     
     
       15. The method according to  claim 13 , wherein step (A) further comprises: 
       connecting both lines of said differential bus to a ground voltage through a first and second pulldown resistor.  
     
     
       16. The method according to  claim 13 , further comprising the step of: 
       improving performance of said device to ESD or EFTB events.  
     
     
       17. The method according to  claim 13 , wherein said device comprises a Universal Serial Bus (USB) peripheral device. 
     
     
       18. An apparatus comprising: 
       a circuit configured to (i) communicate through a differential bus to a device comprising a Universal Serial Bus hub and (ii) execute firmware configured to disconnect and reconnect said circuit to said device in response to an abnormal reset event to provide enhanced electromagnetic compliance (EMC), wherein said apparatus is configured to communicate with said hub through a downstream port.  
     
     
       19. An apparatus comprising: 
       a circuit configured to (i) communicate through a differential bus to a device comprising a Universal Serial Bus peripheral device and (ii) execute firmware configured to disconnect and reconnect said circuit to said device in response to an abnormal reset event to provide enhanced electromagnetic compliance (EMC), wherein said apparatus is configured to communicate with said device through a downstream port.  
     
     
       20. A method for providing enhanced EMC performance in a device, comprising the steps of: 
       (A) generating a zero signal indicating an abnormal reset event in response to a predetermined criteria;  
       (B) communicating through a differential bus to said device;  
       (C) disconnecting and reconnecting said device in response to said abnormal reset event, wherein said device comprises a Universal Serial Bus (USB) peripheral device; and  
       (D) communicating with said device through a downstream port.